Apparatus and method for investing dental patterns



6, 1935. D. w. PHILLIPS APPARATUS AND METHOD FOR INVESTING DENTAL PATTERNS 4Sh eets-Sheet l I 0 Fild Dec. 31, 1931 Aug. 6, 1935. D. .w. PHILLIPS Filed Dec. 51, 1931 4 Sheets-Sheet 2 Aug. 6, 1935. D. w. PHILLIPS APPARATUS AND METHOD FOR INVESTING DENTAL PATTERNS 4 Sheets-Sheet 5 Filed Dec. 31, 1931 1 1935- D. w. PHILLIPS 2,010,700

APPARATUS AND METHOD FOR INVESTING DENTAL PATTERNS Filed Dec. 31, 1951 4 Sheets-Sheet 4 A? '93 92 yf Patented Aug, 6, 1935 .JU STATES.

APPARATUS AND MsTHop FOR INVESTING DENTAL PATTERNS David w; Phillips, Chicago, 111-.

Application December 31, 1931, Serial No. 584,089

. 13 Claims. 'ljhis invention relates to the preparation of dental castings, such as inlays, crowns, bridges,

and the like, and particularly to a'n improved method and apparatus for investing the pattern from which the casting is formed.

The principal object of the invention is to provide a method and apparatus for eifecting. complete distribution of investmentltover the surface.

r scription, which, taken inconnection with the accompanying drawings, discloses a preferred embodiment thereof.

Referring to the drawings: Fig. 1 is a top plan view of the apparatus "which is used to invest the pattern;

Fig. 2 is a longitudinal section through t paratus taken on line 22 of Fig. 1;

,Fig. 3. is a front elevational view of an invest" ment container and the means for supporting the pattern in the container;

. Fig. 4 is a fragmentaryplan view showing the drive means'employed for imparting a turning movement to the investment container; Fig. 5 is a broken side elevational view'of th "container and the drive means for imparting a turning movement thereto;

Fig. 6 is a perspective view of the sprue holder; and

Fig. 7 is a wiring diagram showing the circuits he ap- -for energizing the drive motor and the electric vibrator WhCh is used to vibrate the pattern.

Briefly, the invention consists in the provision ofa method and means whereby the wax casting pattern'may be vibrated while it is embedded in pattern requires not only the vibration of the pattern while it is embedded in the body of inor enveloped by the investment to thereby pre vestrnent in the container, but also requires the removal of the pattern from the container and, the maintenance of the pattern in'a state of continuous vibration while it is removed from the main body of investment and until after it is rev-a inserted threin- As a further aid in preventing the formation of air pockets on the surface of turning movement between the pattern and the body of investment while maintaining thepattern in vibratory condition. As will presently appear,

PA ENT OFFICE the pattern, it is desirable to produce ea relative this turning movement may be either a-movementof rotation or, if prefer ment of oscillation.

Referring to the drawings, w

red, maybe 'a moveherein have shown the preferred embodiment in which I havethus far contemplated applying the principles of the invention, the numeral designates a -base which is formed in separable sections and l3, i

the section I2, as will presently appean: serving as a mount for the investment contairie'randfl the pattern supporting and vibrating means, and a the section l3 serving as afsupportJ-fora drive motor I l. The base is provided on itsunde'r surrubber dam or drum ll, removably secured to the lower end of ring I6, is supported on a table. I8,

ject below stmentcon- 1 ftainer consisting of a cylindrical ring IE and a the latter being keyed to the upper end of a-stub shaft 19 which is journaled in; a beari'ngzZlf mounted in the base. The provision of the rubber drum ll for closing the ring it is'extremely desirable because it not only provides a water-.

tight seal, but also allowsfor setting expansion of the investment. The container, consisting .of,-

ring l6 and drum I1, is arranged to fit snugly, on table 18, the topface of the latter being dished,

or hollowed out, as indicated at 22, to provide; a cavity which fits snugly against the sides and i bottom of drum ii. ,The container and table,- 7

as will presently appear, are arranged to be turned together as a unit, and the closefriction fit between drum i1 and-said cavity, in thetable serves to impart turning movement, fr

cm the table to the container. Y

A wax pattern; indicated at 23, is removabiy 1 supported in the customary mannerlon a coneshapedsprue holder 25, the pattern-being carried on the lower end of a sprue 25 which eX- tends through the tip of the cone, and which is anchored at its upper end in a body of wax El.

The holder 25 is provided with a flange 28 which rests on the upper edge of ring l6, thereby supporting the pattern in proper position in a body of investment 29 lying within the container.

I have found that the difficulties caused by the presence of air bubbles on the surface of the pattern may be effectively overcome by vibrating the pattern while it is enveloped by the investment. I have found that vibration of the pattern, in the manner presently to be described, not only eliminates air bubbles, but also permits the use of one single thick or heavy investment which produces much smoother castings, and allows greater setting expansion of investment, than would be obtainable by the use of thinner single mixes. A single thick mix is, moreover, much to be preferred from the standpoint of ease of manipulation to the commonly used double mix consisting of a thick mix and a thin mix.

In accordance with my invention, I provide means for imparting vibratory movement to the sprue holder 25. This means, which is best shown in Figs. 2 and 3, comprises: a pair of iron core coils 3| and 32 supported on a base plate 33; and an armature 34 which is mounted on a spring arm 35, the latter being riveted to a back plate 36 which projects upwardly from base plate 33. Spring arm 35 bears at its free end against a forwardly extending projection 3? which limits the movement of armature 34 under the action of arm 35. It will be evident that when a current is passed through coils 3i and 32, armature 34 will be pulled downwardly against the cores of the coils and, in accordance with the usual construction of vibrators of this type, the circuit is arranged to be broken between arm 35 and projection 31 when this downward movement of the armature takes place. A rapid interruption of the circuit is thus effected to produce vibration of armature 34 and this vibration is, in turn, me-

chanically transmitted through plates 33 and 35 to sprue holder 25, and thence directly to the item itself. The free end of armature 34 is preferably provided with a screw 38 which serves as a weight for augmenting the vibratory effect set up by the armature. The weight of screw 38 may be varied by threading one or more nuts 39 on the shank thereof.

sprue holder 25 is removably secured to base plate 33 by providing on the under face 'of the latter a spring flange M which yieldingly engages fiange 28 to retain the holder securely in position on the vibrator. As shown in Fig. 3, flange 4| is open along one side to permit holder 25 tobe inserted and withdrawn therefrom by sliding action. Current is supplied to coils 3i and 32 from a plug 42, which is secured by a strip 43 to the base. The posts 44 of plug 42 connect with a suitable source of current supply. A wire'45 carries one side of the line to the vibrator, the return being through a toggle switch 46 (Fig. 1) and a wire 5'! which leads to the plug.

Although the vibrator may be made as a unit which is wholly independent of the base H2, in which case it would be raised and lowered from the investment container by hand, I prefer to provide means whereby the vibrator may be supported upon the base 12 in proper position relative to the ring 16. In the latter case the pattern may either be raised and lowered by hand, or, if preferred, by automatic means presently to be described. In the embodiment shown in the drawings, the base plate 33 of the vibrator is mounted on an arm 48, said plate being provided with a rearwardly extending tongue projection 49 which is telescopically received within a tubular portion 5| carried by arm 48. A coil spring 52 is disposed about the interfitting parts 49 and 5i, one end of said spring being connected to plate 33, and the other end thereof being connected to arm 48. This provides, in effect, a universal joint connection between arm 48 and plate 33. This spring mounting of plate 33 on arm 48 also serves to confine vibration to the pattern and its supporting means.

As shown in Figs. 1 and 2, arm 58 has a double hinge connection with base I2, said hinge consisting of a fixed jaw 53, carried by base I2, and a swinging jaw 54, the latter having pivotal connection at 55 with jaw 53 and also having pivotal connection at 55 with arm 48. A pair of coil springs 51 (Fig. 1), bearing at one end on base l2, and at the other end against swinging jaw 54, serve to normally hold the latter in the vertical position shown in Fig. 2. The forward movement of the swinging jaw or hinge' plate 54 under the action of springs 57 is limited by a block 58 which may be formed as an integral part of base l2. Movement of plate 54 in the reverse direction is 7 limited by a block rest secured to base I2. This rest has a rearwardly inclined face which engages and supports arm 48 when the latter is swung through the vertical position to invert the pattern. It is sometimes desirable to vibrate certain special types of patterns in the inverted position to insure complete distribution of investment without inclusion of air pockets.

The double hinge type of mounting for the vibrator permits the movement of the parts from the position shown by solid lines in Fig. 2 to the position shown by the dotted lines in said figure. Arm 48 may be pivoted in a vertical plane about point 55 and at the same time may be shifted rearwardly while pivoting with jaw 54 about point 55 as a fulcrum. The universal joint connection between plate 33 and arm 43 allows the vibrator to be tilted relative to arm 48 sufiiciently to provide clearance between pattern 23 and the edge of ring 55. Linear, as well as pivotal, movement of the vibrator means is thus provided for, which, when hand operation is employed, enables the operator to remove and replace the pattern in ring it without danger of striking it against the sides of the ring. For example, when plate 33 is tilted upwardly on arm 48, the pattern is thrown to a position where it would strike the forward edge of ring 56 when the operator lowers the vibrator onto said ring. The double hinge mounting of arm 48 avoids this by allowing said arm to be moved to the rear far enough to allow the pattern to clear the edge of the ring.

Means is provided for automatically raising and lowering the pattern relative to the investment container. The mechanism which is provided for this purpose is best shown in Figs. 1 and 2, and comprises: a cam 59 fixedly secured to a shaft 5|, the latter being journaled in bearings 62 carried by block 58; a pin 53, secured to arm 48 and positioned to ride on cam 59; and means for driving to use the vibrator without the automatic drive means. 'As shown in Fig. 2, cam 59. is provided with three separatecam arms 56, 81, and 68. The.

cam rotates in a clockwise directionfas indicatedby the arrow in Fig. 2, and in the position shown in said figure, pin 63 rests on a portion 99 of the cam which allows sprue holder 25 to restflush on the upper edge' of ring l5. As. cam 59 turns from the position shown in Fig. 2, it forces pin 63 upwardly, thereby pivoting arm 48 about point 56 to remove the pattern from the investment. As the cam rotates it will continue to hold arm 48 in the fully raised position until pin 93 engages the inwardly cut. portions on the rear edge of arm 69, whereupon arm' 48 and sp'rue holder 25 fall graduallyuntil the portion ll of the cam engages pin 53. In'this position, sprue holder 25 is i not completely lowered onto ring i6; Further rotation of cam 59 causes arms 61 and 99 to suecessively raise and lower arm 48 and the sprue holder in a similar manner. As will presently appear in'the description of Fig. 7, the normal starting point for rotation of cam 59 is the position in which the outermost portion of arm 65 engages pin 53. Also, as will presently appear, an automatic cut-off is provided for stopping rotation of said cam in the position shown in Fig. 2.

Each operative cycle, therefore, involves first, a very gradual lowering of the pattern into the investment, second, a gradual removal of the pattern from the investment, followed by a period in which the pattern is held removed from the investment, this being accomplished by arm 61; third, a lowering of the patterninto the investment, this being effected by the. portion 12 of cam 59; and finally, a second raising and lowering of the pattern, this being effected by arm 69 of cam 59, this last operation resulting in the positioning of ,holder 25 fiush on the top of ring it. During this sequence of steps the pattern is maintained in a continuous state of vibration. This sequence of operations under continuous vibration of the pattern, as herein-described, has beenfound to be remarkably effective in ob- ,taining a thorough distribution of investment over the entire pattern and in removing air bubbles from the surface of the pattern even when a single heavy mix is used.

I prefer to provide in conjunction with the means for automatically raising and lowering the pattern, means for producing a relative turning movement betweenthe body of investment and thepattern: This is accomplished by the provision of mechanism for imparting a turning movement to table I8, the mechanism, in the embodiment shown, being arranged to effect either a movement of rotation, or a movement of oscillation of said table as may be desired. Thismecha'nism is shown in Figs. 2, 4,and 5.,

. and comprises: a'spur'gea'r l3, fixedly secured to shaft [9; a spur wheel 14 fixedly secured to a' stub" shaft 15, the latter being journaled in a bearinglfi carried by base"|2;' a horizontally disposed plate Tl arranged to pivot on shaft 15;

; a pair of spur gears 18 and l9,-pivoted at 8| and 82,. respectively, on plate ll, gear 18 being positioned to be in permanent driving engagement with spur wheel M; a drive shaft 83, journaled inbearings '84 and 85, and having driving engagement with shaft-15 through a pair of pinions "between shafts GI and 83; and cam means for shifting plate H to effect reversal in the direction of drive of table supporting shaft |9, said last-mentioned means including. a cam 9|, se-

cured to shaft 6|, and a follower arm ,92 having.

a roller 93at one end for riding on .cam 9| and having at its opposite end a pin 94 which engages a slot 95 in plate ll.

In the position of the parts shown in Figs. 4' and,5, table supporting shaft I9 is rotated in a clockwise direction, the drive from shaft 15 being through spur wheel 15 and spur gear 18. As soon as main drive shaft 6| turns sufliciently to bring one of thecam projections 95 against roller 93,

arm 92 will be moved to the right, thereby pivoting plate 11 sufiiciently to remove gear 18 from driving engagement with gear 13, and at the same time moving. gear 19 into driving engage on the frame, urges arm 92 toward cam 9|, there by insuring that roller 93 will follow the surface irregularities in cam 9|.

I provide means whereby a movement of rotation may be imparted to table supporting shaft i9 instead of a movement of oscillation. To this end I provide a removable pin 98 which is adapted to be inserted through a hole inplate H, the lower end of said pin being received in'either one of two openings (not shown} provided in base l2. It will be apparent that by inserting pin 98 through plate 11 and into the base |2,

pivotal movement of plate 11 underthe' actionof arm 92, is prevented, so that plate 11 will be) held in such position as to drive shaft I9 in one direction or the other, depending upon whether gear 18 or gear 19 is positioned to engage gear 13. In order to allow for continued movement of arm 92 on cam 9|, even though plate l'lbe held against movement, I provide in said arm 92 a telescoping spring connection consistingof a hollow arm portion 99 which contains a coil spring the latter serving to take up the motion imparted to theportion of arm 92 which carries roller 93. The gear ratio between shaft 6| and table supporting shaft l9 ispreferably speed of about from one to three revolutions per minute.

the apparatus. A pair of main line wires I92 source of current supply. If it is desired to use only the base portion l2, without the automatic drive means, it is merely necessary to close toggle "switch 46 to supply currentto the vibrator coils 3| and 32. However, thecircuit to coils 3| and 32 is so arranged that when the automatic drive means carried by base I3 is coupled to base .|2, the control of the vibratorrnay be effected from 1 the same switch which controls motor l4. To this end, as will be noted from Fig. 1, there is provided on base |.2, a pair of terminal plugs I99 and |95which are positioned to engage, respec such as will give a turning of the table at a H and I93 are arranged to connect with a suitable Y tively, with a second pair of plugs |06 and I01 carried by base l3. These plugs interconnect with one another, as shown in Fig. 1, when base portions 2 and I3 are placed into registration with one another, it being also noted from said 91, extendingbetween plate TI and a fixed point a 1 I 55 1: In Fig. 'II have shown a wiring diagram for figure that clutch collar 64 completes the'connection between gear box 65 and shaft 6! when the two base portions are thus coupled together. The breaks in the circuit afforded by plugs l 04I01 are indicated in Fig. 7 by the three pairs of converging arrows 698.

The feed to motor M is taken from main line wire I03 through a wire E09 and an automatic cut-out switch Hi] to a wire Hi which connects with the motor, the return being from the motor through wires H2 and i 53 to a toggle switch i iii, the latter connecting through a wire M5 to the other main line wire 52. When the automatic drive means is used, toggle switch it on base i2 --is opened. The feed to the vibrator coils 3i and cuit is now through switch i M instead of through switch 46.

Switch llii, which is arranged in series with motor I i-and switch H5, is provided to automaticallyicut off the automatic drive when the pattern has been lowered'into final position in the investment. This switch is shown in Fig. i and consists of a lever H8, pivoted at lid to the base, and provided at one end with a roller iiii which rides ona cam disc E22, the latter being arranged to rotate with clutch collar 5d. The opposite end of lever H8 carries one of the contacts of switch Hi), the other contact of said switch, which is indicated at E23, being engaged by the contact on lever M8 when the latter is in the position shown in Fig. 1. v A cam groove I2 1- is provided in cam disc 22 and is positioned toreceive cam roller i2i, a coil spring 925 being provided for pivoting lever M8 to the right, ViewingFig. 1, to hold roller iiii against cam disc I22. Cam groove i2 1 is so positioned relative to cam 59 that it will receive roller iii at the point when the portion-6Q of said cam 59 engages pin 63, this being the point at which sprueholder 25 is flush on the top of ring i5. i2] is thrust into cam groove i2 i, lever i 58 is pivoted sufficiently to open switch 5 it, thereby opening the circuit through motorltl and stopping rotation of shaft 6!. Although the motor thus .ceases to operate, the vibrator continues to run until toggle switch lid is opened.

In order to advance shaft 6! from the normal stopping position shown in Fig. 2, to the starting position with pin filiresting on the outermost portion of arm 66, it is merely necessary to turn. 'lever H8 with the finger in a counter-clockwise direction, viewing Fig. 1,, sufiiciently to close switch I it. This will start operation of motor l4, thereby turning cam 59 sufiiciently to raise the vibrator to its normal inactive position, at which point the toggle switch MB is opened to open the circuit to motor i l. During this slight rotation of shaft 5! cam disc 5 will have turned sufficiently to hold lever H3 in circuit-closing position and another'cycle of operations is inaugurated by merely closing toggle switch i M.

The foregoing detailed description has'been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, but the appended claimsshould be construed as broadly as permissible in view of the prior art.

What I regard as new and desireto secure by Letters Patent is:

1. The method of investing a castingpattern As cam roller which comprises inserting the pattern into the investment contained in a stationary flask with the pattern under vibration, and continuing vibration of the pattern while enveloped by the investment to thoroughly adapt the investment material to the surface of the pattern without trapping air about the invested pattern.

2. The method of investing dental patterns which consists in inserting the casting pattern in the investment, vibrating the pattern while enveloped by the investment to prevent the formation of air bubbles on the surface of the pattern, removing the pattern from the body of investment while continuing vibration of the pattern, maintaining the pattern in vibratory condition while removed from the body of investment to eliminate air bubbles between the surface of the pattern and the investment adhering thereto and finally embedding the pattern in the body of the investment.

3. The method of investing dental patterns which consists in inserting the casting pattern in the investment while vibrating the pattern, vibrating the pattern while enveloped by the investment to prevent the formation of air bubbles on the surface of the pattern, removing the pattern from the body of investment while continuing vibration of the pattern, maintaining the pattern in vibratory condition while removed from the body of investment to eliminate air bubbles between the surface of the pattern and the investment adhering thereto and finally embedding the pattern in the body of the investment.

4. The method of investing dental patterns which consists in inserting the casting pattern in the investment, vibrating the pattern while enveloped by the investment to prevent the formation of .air bubbles on the surface of the pattern, repeatedly removing the pattern from and re-inserting it into the body of investment while maintaining the pattern in a state of continuous vibration and finally embedding the pattern in the body of the investment.

5. The method of investing dental patterns which consists in vibrating the casting pattern while enveloped by the investment to prevent the formation of air bubbles on the surface of the pattern, and simultaneously producing a relative turning movement between the pattern and the body of investment ,to aid in removal of air pockets from the surface of the pattern.

6. The method of investing dental patterns which consists in inserting the casting pattern in the investment, vibrating the pattern while enveloped by the investment to prevent the formation of air bubbles on the surface of the pattern, producing a relative turning movement between the pattern and the body of investment to eliminate air pockets from the surface of the pattern, removing the pattern from the body of investment while continuing vibration of the pattern, maintaining the pattern in vibratory condition while removed from the body of investment and finally embedding the pattern in the body of the investment.

7. The method of investing dental patterns which consists in introducing the pattern into a miX 'of investment material contained in a stationary, open-top flask by gradually dipping the pattern down into the investment while the pattern is under vibration until it is completely pattern in the investment, and terminating the vibration of the pattern.

8. Apparatus for investing a dental pattern, comprising an investment container, a base, means on said base for supporting said container in fixed position, a combination crucible former and pattern support arrangeable upon an open end of said container, means pivotally supported on said base and connectible with said combination crucible former and pattern support for moving the latter, whereby the pattern may be embedded, removed and re-embedded in the investment contained in said container, and a vibrating device connected with said last mentioned means for producing vibratory motion of the same and of the attached pattern in all positions thereof, whether the pattern be embedded in the investment or removed therefrom.

9. Apparatus for investing a dental pattern, comprising an investment container, a base, means on said base for supporting said container in fixed position, a combination crucible former and pattern support arrangeable upon an open end of the said container, means pivotally spported on said base and connectible with said combination crucible former and pattern support for moving the latter, whereby the pattern may be embedded, removed and re-embedded in the investment contained in said container, and a vibrating device connected with said last mentioned means for producing vibratory motion of the same and of the attached pattern in all positions thereof whether the pattern be embedded in the investment or removed therefrom, said pivotally supported'means'having a flexible joint therein whereby the pattern support may be centered on the container and removed without causing the pattern to strike the wall of the container.

a 10. Apparatus for investing a dental pattern, comprising an investment container, a base, means on said base for supporting said container in fixed position, a hinge attached to said base, a swinging arm pivotally connected to said hinge, a combination crucible former and pattern support attachable to the free end of said arm, the latter having a clamp for securing said crucible former and pattern support in place, a vibrating device carried by said arm and adapted to impart vibration to the pattern as it is raised from.

comprising, an investment container, a base, means on said base for supporting said container in fixed position, a hinge attached to said base, a swinging arm pivotally connected to said hinge, a combination, crucible former and pattern support attachable to the free end of said arm, the latter having a clamp for securing said crucible former and pattern support in place, a vibrating device carried by said arm and adapted to impart vibration tothe pattern as it is raised from and lowered into the investment, a cam positioned adjacent said arm to raise and lower the same, thereby inserting and removing the pattern from the investment repeatedly and at predetermined speed solong as said cam continues to operate, and means for operating said cam, said arm being movable by hand independently of said cam when desired.

12. Apparatus for investing a dental pattern comprising, an investment container, a base, means on said base for supporting said container in fixed position, a hinge attached to said base, a swinging arm pivot-ally connected to said hinge, a combination crucible former and pattern support attachable to the free end of said arm, the latter having a clamp for securing said crucible former and pattern support in place, a vibrating device carried by said arm and adapted to impart vibration to the pattern as it is raised from and lowered into the investment, a cam positioned adjacent said arm to raise and lower the same, thereby inserting and removing the pattern from the investment repeatedly and at predetermined speed so long as said cam continues to operate, means for operating said cam, said arm being movable by hand independently of said cam when desired, and means operatively connected with said container supporting means for turning the latter while said pattern is being inserted in and removed from the investment in said container.

13. Apparatus for investing a dental pattern, comprising an investment container, a base, means on said base for supporting said container in fixed position, a combination crucible former and pattern support arrangeable upon an open end of said container, means supported on said base and connectible with said combination crucible former and pattern support for moving the latter, whereby the pattern may be embedded, removed and re-embedded in the investment contained in said container, and a vibrating device connected with. said last mentioned means for producing vibratory motion of the same and of the attached pattern in all positions thereof, whether the pattern be embedded in the investment or removed therefrom.

DAVID W. PHILLIPS. 

